I made this base for a Storm Strider that I painted for Mark. I had a couple different ideas for making this base, but when I started working on it this method came to me.
Step 1: I cut a circle from a piece of HO scale fieldstone plasticard. To fit inside the lip of a 120mm base, the circle needs to be 108mm.
Step 2: Basecoat the base. The color of the stone is going to be the color of your design, not the rest of the area.
Step 3: I print out a Cygnus, cut it out, transfer it to a thin piece of plasticard, and cut that out, making a stencil of sorts.
Step 4: I spray paint the base with Army Painter Green Ochre. Its the German desert tank color for Flames of War. Remove the stencil to reveal a blue Cygnus.
Step 5: Trace around the design with a hobby knife. Just score it enough to make a division between the two colors.
Step 6: Wash the base with a brown wash. You can see how the wash sits in that knife scar and divides the stonework.
Step 7: Drybrush the stones to finish off the effect.
Step 8: Paint the rim and glue a model to it!